1. Field of the Invention
The present invention relates to an electrodeless lamp, and particularly, to a lamp bulb for an electrodeless lamp in which a discharge material for forming plasma therein is filled.
2. Description of the Background Art
Generally, an electrodeless lamp is an apparatus for emitting light by exciting discharge material filled in an electrodeless bulb to form plasma.
FIG. 1 is a block diagram showing a general electrodeless lamp.
As shown therein, a general electrodeless lamp comprises: a microwave generator 10 for generating microwave or radio frequency energy by being applied an outer electric power (not shown); a waveguide 20 connected to the microwave generator 10 for transmitting the microwave generated in the microwave generator 10; a resonating device 30 having an inner space for resonating the microwave transmitted through the waveguide 20 by making an outer wall thereof as a mesh structure; and a bulb 40 installed in the inner space of the resonating device 30 for emitting light as being excited by the microwave.
On the other hand, the bulb 40 comprises an envelope which is able to permeate the light, and filled material for forming plasma by the microwave to emit the light filled in the envelope with buffer gas comprising argon (Ar), etc.
Also, the bulb 40 is coupled to a rotational shaft 52 extended from a rotating motor 51 which is positioned on an outer side of the resonating device 30 so as to be rotated for cooling.
An operation of the general electrodeless lamp having above described structure will be described as follows.
When the electric source is applied, the microwave generator 10 generates microwave, and the microwave transmitted to the resonating device 30 through the waveguide 20 excites the filled material filled in the bulb 40 to form the plasma, and thereby the light is emitted.
At that time, the bulb 40 generates a lot of heat as forming the plasma therein, and the bulb 40 is cooled down by being rotated according to the operation of the rotating motor 51.
On the other hand, the electrodeless lamp comes to have different characteristics according to the filled material and the buffer gas which are filled in the bulb 40. Especially, a light emitting efficiency, an energy efficiency, initial lighting, re-lighting time, and stability are differentiated according to the buffer gas filled inside the bulb 40.
In addition, the general electrodeless lamp can be re-lighted only after a predetermined time (tens of secondsxcx9cfew minutes) has passed when the light is put out. It is caused by that a pressure of neutral gas in the bulb is too high, and therefore sufficient mean free path of electron having the energy needed to discharge the plasma can not be ensured.
Therefore, in order to reduce the re-lighting time, a method such as blowing a strong wind directly to the bulb to reduce the pressure in the bulb has been tried. However, problems such as increasing of cost as an additional device is disposed, reliability of the additional device, utilization of the space around the bulb, and shielding the light from the bulb by a nozzle are generated.
On the other hand, according to U.S. Pat. No. 6,084,348 as one of conventional arts for reducing the re-lighting time of the electrodeless lamp, a first component which is a participle component emitting the light when the high frequency energy is excited, a second component selected from a group of Xe and Kr and assigned to have a predetermined partial pressure, and a third component selected from a group of Ar, Ne, and He, and assigned to have a predetermined partial pressure are included in the bulb of the electrodeless lamp, and the partial pressure of the second component is larger than that of the third component. The pressure of second component is in a range of 50xcx9c200 torr, and the pressure of third component is in a range of 5xcx9c20 torr.
In the electrodeless lamp shown in U.S. Pat. No. 6,084,348, the Xe, that is, the second component has relatively higher light emitting efficiency in the most preferred embodiment. However, according to experiments, the initial lighting or the re-lighting is difficult, and therefore, a large electric field, that is, high frequency energy is needed in initial lighting, and the re-lighting time may be increased or the re-lighting may not be made.
Therefore, an object of the present invention is to provide a bulb for an electrodeless lamp by which re-lighting after putting out light can be made easily, and re-lighting time can be reduced.
To achieve the object of the present invention, as embodied and broadly described herein, there is provided a bulb for an electrodeless lamp comprising: an envelope through which the light can be permeated; a filled material filled in the envelope for emitting the light as being excited by high frequency energy; and buffer gas, comprising first buffer gas, and second buffer gas having a partial pressure less than 1% of the partial pressure of the first buffer gas in order to reduce a discharging voltage and lighting time.
Also, there is provided a bulb for an electrodeless lamp comprising: an envelope through which the light can be permeated; a filled material filled in the envelope for emitting the light as being excited by high frequency energy; and buffer gas, wherein the buffer gas comprises first buffer gas selected from a group including Ne and Xe, and second buffer gas including Ar having a partial pressure less than 1% of the partial pressure of the first buffer gas in order to reduce a discharging voltage and lighting time.
Also, there is provided an electrodeless lamp comprising: a microwave generation unit for generating microwave; a waveguide unit coupled to the microwave generation unit for transmitting the microwave generated from the microwave generation unit; a resonance unit connected to the waveguide unit for resonating the microwave which is transmitted through the waveguide; and a bulb unit disposed in the resonance unit for emitting light as being excited by the microwave, wherein the bulb unit comprises: an envelope through which the light can be permeated; a filled material filled in the envelope for emitting the light as being excited by high frequency energy; and buffer gas, comprising first buffer gas, and second buffer gas having a partial pressure less than 1% of the partial pressure of the first buffer gas in order to reduce a discharging voltage and lighting time.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.